This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 0 |
| 4 | 1 |
| 5 | 1 |
| 6 | 4 |
| 7 | 8 |
| 8 | 25 |
| 9 | 64 |
| 10 | 191 |
| 11 | 540 |
| 12 | 1616 |
| 13 | 4785 |
| 14 | 14512 |
| 15 | 44084 |
| 16 | 135545 |
| 17 | 418609 |
| 18 | 1302340 |
| 19 | 4070124 |
| 20 | 12785859 |
| 21 | 40325828 |
| 22 | 127689288 |
| 23 | 405689020 |
| 24 | 1293060464 |
| 25 | 4133173256 |
| 26 | 13246527139 |
| 27 | 42557271268 |
| 28 | 137032656700 |
| 29 | 442158893833 |
| 30 | 1429468244788 |